Field of the Invention
The present invention relates to a radar antenna device and particularly to the arrangement for controlling electric power supply thereto when the device is started to operate.
Background Information
A conventional radar antenna is comprised with a rotating antenna for successively emitting and receiving radio waves, a transmission circuit for generating transmission signals emitted as radio waves into an outer space, and a motor for rotating the antenna. The rotational movement of the radar antenna is affected by winds blowing in a surrounding environment. If a radar antenna is installed in a moving body, it is also affected by wind pressures due to movements of the moving body. There have been known radar antennas to control the motor in coping with these wind affects. Radar antennas of this kind have been disclosed in Japanese unexamined patent application publications 2000-139090 and 2005-98950.
The radar antennas disclosed in these Japanese patent application publications are comprised with detection units for detecting rotational speeds of antenna units, and control motors in response to the rotational speed thereof. The control will prevent large rotational speed fluctuations to stabilize the rotational speed of the antenna units.
A radar antenna is coupled to an electric power source and is supplied with electric power therefrom. The electric power supplied is used for computations, emissions of transmission signals, and motor drives to rotate an antenna. Such electric power sources are required to have a capacity to supply electric power as much as the total maximum amount of the electric power required for the respective uses in order to avoid without failures electric power shortages.
In particular, high electric power has been required for emitting transmission signals and driving the motor when the antenna unit is started to be driven. Thus, a big capacity of the electric power source has been required. But, such electric power sources having the big capacity have been large in size and high in manufacturing cost, which should be improved.